How to collect and store the coefficient of symbolic differential equation ?

I am trying to model dynamics of 3 link manipulator using EL method using symbolic eqn in matlab and now I want to collect the coefficient of theta_ddot, theta_dot, theta to make M matrix, C matrix, and h matrix.

Answer 1

[Sam Chak]

Hi Akash,

You can try using coeffs and see if it works for you. Examples are shown in the link.

https://www.mathworks.com/help/symbolic/sym.coeffs.html

[Akash Vyas]

coeff is not working in this case, since eqn is

and I want to find M matrix, but coeff is giving me

[Walter Roberson]

coeffs(rhs(Equation), thetadotdot)